The present invention relates to the general field of nacelles fitted to bypass turbojets, and it relates more particularly to nacelles that are mounted on the fuselage of an airplane.
The nacelle of a bypass turbojet comprises in particular an aerodynamic fairing that is fastened to the airplane or on the engine and that includes one or more maintenance covers, a cold stream outer shroud placed inside the aerodynamic fairing, and a cold stream inner shroud placed inside the outer shroud and co-operating therewith to define an annular flow passage for a cold stream (or secondary stream). The central spool of the turbojet is housed inside the inner shroud and it delivers a hot stream (or primary stream).
There are two main types of nacelle: nacelles that are fastened under an airplane wing, and nacelles that are fastened to the fuselage of an airplane (generally towards its tail). The invention relates more particularly to nacelles of the second type.
Compared with nacelles fastened under an airplane wing, nacelles mounted on an airplane fuselage have the particular feature that the inner and outer shrouds are in the form of single pieces or of half-shells. Access to the central spool for maintenance operations thus takes place through openings formed in the inner and outer shrouds, these openings being closed in operation by hatches that are screwed onto the respective shrouds.
Such a nacelle structure nevertheless presents certain drawbacks. In particular, in order to perform a maintenance operation on the central spool of the turbojet (e.g. for performing endoscopy, replacing spark plugs, or removing sensors), it is necessary in succession to open the maintenance covers in the aerodynamic fairing, to remove the hatches in the outer shroud, and to remove the access hatches in the inner shroud. The time required for maintenance is thus unduly lengthened because of these time-consuming operations. Furthermore, since maintenance technicians need to be able to access the central spool of the turbojet with standard tools and sometimes cold weather equipment, it is necessary to provide arrangements on the hatches that may make the turbojet heavier (e.g. providing them with large handles). Finally, the operation of installing/removing the hatches gives rise to risks of error during maintenance (e.g. putting a hatch back wrongly).